JP2019035934A - Reflective plate with projections - Google Patents

Abstract

To provide a reflective plate preferred for a constitution member such as direct backlight unit.SOLUTION: The reflective plate comprises: multiple projections of 1 mm or more in height, in which the load resistance of the projection is 3 N or more, the maximum thickness D is 400 μm or more, the horizontal cross-sectional area of the projection decreases as the height increases, the specific gravity of the reflective plate having the projections is 0.5-1.1, the ratio d/D between the minimum thickness d and the maximum thickness D of the reflective plate with the projections is 0.5-0.8, and bubbles including a core are contained. In the multiple projections, the difference Δh between the maximum value and the minimum value in height is 0.5 mm or less. The reflective plate is formed of polyester as the major component, and has at least three layers.SELECTED DRAWING: None

Description

  The present invention relates to a reflector having a projection that is suitably used as a component of a direct type backlight unit or the like.

  In recent years, many displays using liquid crystals have been used as display devices for personal computers, televisions, smartphones, tablets, mobile phones and the like. Since these liquid crystal displays themselves are not light emitters, they can be displayed by installing a surface light source called a backlight from the back side and irradiating light. Further, the backlight has a structure of a surface light source called an edge light type or a direct type in order to meet the demand for not only irradiating light but also irradiating the entire screen uniformly. In particular, for thin liquid crystal display applications used in notebook computers, monitors, tablets, etc., where thinness and miniaturization are desired, edge-light type backlights that irradiate light from the side are applied. ing. On the other hand, for a large screen such as a liquid crystal television, a backlight of a direct type, that is, a type of irradiating light from the back surface to the screen is applied.

  Lamp reflectors and reflectors used in such surface light sources for liquid crystal screens (hereinafter sometimes collectively referred to as reflective films, surface light source reflecting members, etc.) are required to have high light reflection performance. A film to which is added, a film containing fine bubbles inside, or a film obtained by bonding these film and a metal plate, a plastic plate or the like has been used. In particular, a film containing fine bubbles inside is widely used because it has a certain effect in improving luminance and uniforming screen luminance (Patent Documents 1 and 2).

  In the direct type backlight, a diffusion plate or an optical sheet is used. The LED and the diffusion plate can be sufficiently diffused by placing them at a certain distance, but it is difficult to maintain the distance only by the strength of the diffusion plate, particularly in a large television. As a method for solving this problem, conventionally, a plastic support pin for supporting the diffusion plate is used (Patent Document 3). However, since the processing cost for arranging the pins and the reflectance of the pins themselves are low, there is a problem that shadows and unevenness are likely to occur.

JP 2003-160682 A Japanese Patent Publication No. 8-16175 International Publication No. 2014/185543

  An object of the present invention is to solve the above problems and to provide a reflecting plate suitable for a component such as a direct type backlight unit.

As a result of intensive studies on the problem, the present inventors have found that the above-described problem can be easily solved if a reflector having the following configuration is used, and the present invention has been completed.
(1) A reflector having a protrusion having a height of 1 mm or more.
(2) The reflector according to (1), wherein the load resistance of the protrusion is 3N or more.
(3) The reflector according to (1) or (2), wherein the maximum thickness D is 400 μm or less.
(4) The reflecting plate according to any one of (1) to (3), wherein a horizontal cross-sectional area of the protrusion decreases according to height.
(5) The reflecting plate according to any one of (1) to (4), wherein the reflecting plate having a protrusion has a specific gravity of 0.5 to 1.1.
(6) The reflecting plate according to any one of (1) to (5), wherein a ratio d / D between the minimum thickness d and the maximum thickness D of the reflecting plate having protrusions is 0.5 or more and 0.8 or less.
(7) The reflecting plate according to any one of (1) to (6), which contains bubbles that enclose a nucleus.
(8) The reflecting plate according to any one of (1) to (7), including a plurality of the protrusions, and a difference Δh between a maximum value and a minimum value of the height is 0.5 mm or less.
(9) The reflector according to any one of (1) to (8), wherein the main component is polyester.
(10) The reflecting plate according to any one of (1) to (9), comprising at least three layers.
(11) The reflecting plate according to any one of (1) to (10), which is used for an LED lighting unit.
(12) The reflector according to any one of (1) to (10), which is used in a direct type LED backlight unit.

  ADVANTAGE OF THE INVENTION According to this invention, the reflecting plate which has the processus | protrusion excellent in the intensity | strength which supports a reflecting plate and a diffusion plate, for example can be provided.

  As a result of intensive studies on the problem, the present inventors have determined that it is important to have not only high reflectivity and moldability but also high strength in order to obtain a reflector having protrusions. It came to make. Televisions and displays are usually used in a state where the screen is vertical, but assembly is performed in a state where the screen is tilted horizontally. At that time, the distance between the LED and the diffusing plate cannot be maintained unless the protrusion has strength to support the weight of the optical film group including the diffusing plate. If the distance between the LED of the direct type backlight unit and the diffusion plate is not maintained, the diffusibility is not sufficiently exhibited and the brightness unevenness of the LED occurs.

  As a result of intensive studies by the present inventors, by using a reflector having a protrusion having a height of 1 mm or more, the protrusion plays the role of a support pin, thereby supporting the diffusion plate and brightness of the LED. It has been found that unevenness can be improved.

[Film structure]
The reflector of the present invention is characterized by having a protrusion having a height of 1 mm or more. If the height of the protrusion is less than 1 mm, the distance between the diffusion plate and the LED may not be maintained. The height of the protrusion is preferably 30 mm or less. More preferably, they are 2 mm or more and 25 mm or less, Especially preferably, they are 3 mm or more and 20 mm or less. If the height of the protrusion is larger than 30 mm, for example, when the protrusion is formed by molding, it may be difficult to provide sufficient strength because the reflector becomes thin. The shape of the protrusion is not particularly limited, but it is preferable that the center of gravity of the bottom surface and the center of gravity of the entire solid exist on the same straight line in the film thickness direction, because sufficient strength can be given, and the cone Shape, frustum shape, hemispherical shape, spherical crown shape, columnar shape, a combination thereof, intermediate shape, a shape that is distorted like an ellipse, or a shape with rounded corners with rounded corners. Of these, a conical shape and a truncated cone shape are preferable because both the ease of forming and the strength of the protrusions are easily achieved. The protrusion having a height of 1 mm or more can be obtained by, for example, molding a film or sheet used as a reflector. In the present invention, a film having a thickness of 400 μm or less is referred to as a “film”, and a film having a thickness greater than 400 μm is referred to as a “sheet”. The reflector of the present invention may be a film or a sheet.

  The forming method is not particularly limited, but a method of forming only a film, such as vacuum forming, pressure forming, vacuum pressure forming, press forming, plug assist vacuum pressure forming, insert forming, TOM (Three Dimension Over Method) forming, tertiary It can be formed by a generally known forming method such as a forming method with a base material such as original laminate forming.

  In the reflector of the present invention, it is preferable that the load resistance of the protrusion is 3N or more. More preferably, it is 5N or more, More preferably, it is 10N or more. When the load resistance is less than 3N, the protrusion may not be able to withstand the mass of the diffusion plate or the optical film during assembly. The load resistance of the protrusion is preferably high, but in order to achieve the protrusion with a height of 1 mm or more, it is preferably 50 N or less. The method for setting the load resistance to a range is not particularly limited, but the configuration of the reflector described below is preferable.

  The reflective plate of the present invention preferably has a maximum thickness D of 400 μm or less. If the maximum thickness is greater than 400 μm, R at the tip of the protrusion may become too large. If R at the tip of the protrusion becomes too large, the contact portion between the reflecting plate and the optical film group such as the light guide plate and the diffusing plate may become dark and uneven. More preferably, they are 100 micrometers or more and 350 micrometers or less, More preferably, they are 150 micrometers or more and 300 micrometers or less. When the maximum thickness D of the reflector is less than 100 μm, the strength of the protrusion may be insufficient.

In the reflector of the present invention, it is preferable that the horizontal cross-sectional area of the protrusions decreases according to the height. As the horizontal cross-sectional area decreases with the height, it becomes easy to disperse the load. As a result, the load resistance is easily improved, which is preferable. If the horizontal cross-sectional area does not decrease with height, there may be a place where the load tends to concentrate. This horizontal cross-sectional area indicates the area surrounded by the outer periphery of the protrusion when the protrusion is cut horizontally regardless of the thickness of the reflector. That is, the flat cross-sectional area of the protrusion decreases with the height. The height of the protrusion is h, the cross-sectional area horizontally cut at the height _x is S _(x) , and the cross-sectional area horizontally cut at the height y is the when the _{S (y),} any h>x>y> 0 and becomes x, with respect to _y, refers _{to S (x) <S (y} ) is established. Furthermore, the cross-sectional area which is cut horizontally at a height _{2 / 3h S (2 / 3h} ), when the cross-sectional area which is cut horizontally at a height 1 / 3h and _{S (1 / 3h), S} (2 / 3h) And S _{(1 / 3h)} preferably satisfy (Expression).
0.25 ≦ S _{(2 / 3h)} / S _{(1 / 3h)} <0.7 (formula).

If it is smaller than this range, the strength of the central portion of the protrusion in the height direction (the portion of 1 / 3h <x <2 / 3h) is too steep and the strength may be insufficient. Moreover, when larger than 0.7, the front-end | tip part (part of 2 / 3h <x <h) of a processus | protrusion is too sharp, or the side part of a standup | rising part (part of 0 <x <1 / 3h) is too steep. Therefore, the strength may be insufficient. When the shape of the protrusion is a perfect cone, S _{(2 / 3h)} / S _{(1 / 3h)} is always a constant value of 0.25. However, in the present invention, the shape of the protrusion is conical. S _{(2 / 3h)} / S _{(1 / 3h)} is preferably larger than 0.3 and smaller than 0.5.

  The protrusion in the reflector of the present invention preferably has a bottom surface width that is less than 10 times the height. Although details of the measurement method will be described later for the bottom surface width, the protrusion is observed from directly above, and the longest width is defined as the bottom surface width. More preferably, it is less than 8 times, More preferably, it is less than 5 times. When the width of the bottom surface is 10 times or more of the height, the component in the perpendicular direction when the component of the load force acting at the contact point between the projection and the diffusion plate or the optical film is decomposed into the tangential direction and the perpendicular direction becomes large. As a result, the strength may be insufficient. The bottom surface width is preferably larger than the height, more preferably the bottom surface width is larger than twice the height. If the bottom width is less than or equal to the height, formability may be insufficient.

  In the reflector of the present invention, the reflector having a protrusion preferably has a specific gravity of 0.5 or more and 1.1 or less. More preferably, they are 0.6 or more and 1.05 or less, More preferably, they are 0.7 or more and 1.0 or less. If the specific gravity is less than 0.5, the strength of the protrusions may be insufficient. If the specific gravity is greater than 1.1, it may be difficult to sufficiently increase the reflectance of the reflector. The method for setting the specific gravity in such a range is not particularly limited, but a method of containing bubbles inside the reflector is preferably used. As a method of containing bubbles in the interior, (1) a method in which a foaming agent is contained in the thermoplastic resin (A), foamed by heating during extrusion or film formation, or foamed by chemical decomposition to form bubbles, (2) A method of adding a gas or a vaporizable substance at the time of extrusion of the thermoplastic resin (A), (3) inorganic particles and / or thermoplastic resin incompatible with the resin (B) in the thermoplastic resin (A) In the present invention, it is easy to adjust the amount of bubbles contained in the film, and the production of the fine bubbles by uniaxial or biaxial stretching. From the comprehensive point of view such as cost, it is preferable to use the above method (3).

  As the inorganic particles in the method (3), silica, colloidal silica, calcium carbonate, aluminum silicate, calcium phosphate, alumina, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide (zinc white), antimony oxide, cerium oxide, Zirconium oxide, tin oxide, lanthanum oxide, magnesium oxide, barium carbonate, basic lead carbonate (lead white), barium sulfate, calcium sulfate, lead sulfate, zinc sulfide, mica, mica titanium, talc, clay, kaolin, etc. Particles. Further, they can be used alone or in combination of two or more. Among them, barium sulfate particles, titanium dioxide particles, and calcium carbonate are particularly preferable because film formation stability can be obtained with high optical characteristics. When air bubbles are included in the inorganic particles, the inorganic particles are preferably contained in an amount of 1 to 50% by mass with respect to the total mass of the reflector of the present invention. When the inorganic particles are less than 1% by mass, it is difficult to make the specific gravity 1.1 or less. When the inorganic particles are more than 50% by mass, the mechanical strength, heat resistance, and production cost of the thermoplastic resin (A) may be impaired. is there.

  When the thermoplastic resin (A) is added to the thermoplastic resin (B) that is incompatible with the resin, and the fine bubbles are generated by uniaxially or biaxially stretching it, the thermoplastic resin (A) is a polyester. A resin is preferred. About a polyester resin, a preferable aspect is described below. The polyester resin refers to a polymer having an ester bond in the main chain, and the polyester resin used in the present invention is preferably a polyester resin having a structure obtained by condensation polymerization of dicarboxylic acid and diol. As the dicarboxylic acid component, for example, aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodium sulfone. Aromatic dicarboxylic acids such as dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids And oxycarboxylic acids such as paraoxybenzoic acid. Further, as dicarboxylic acid ester derivative components, esterified products of the above dicarboxylic acid compounds, such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, adipic acid Examples of the components include dimethyl, diethyl maleate, and dimethyl dimer. Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -Aliphatic dihydroxy compounds such as hexanediol, 2,2-dimethyl-1,3-propanediol (neopentylglycol), polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, 1,4 -Each component, such as alicyclic dihydroxy compounds, such as cyclohexane dimethanol and spiroglycol, and aromatic dihydroxy compounds, such as bisphenol A and bisphenol S, are mentioned. These may be used alone or in combination of two or more. A copolyester resin may be used as the polyester resin used in the present invention. It is preferable that two or more of the copolymerized polyesters listed as the dicarboxylic acid component of the polyester resin and / or two or more of the copolymerized polyesters listed as the diol component are copolymerized. As a method for introducing the copolymer component, a copolymer component may be added at the time of polymerization of the polyester pellets as a raw material, and the copolymer component may be used as a pellet in which the copolymer component is polymerized in advance. For example, polyethylene naphthalate is used. Alternatively, a method may be used in which a mixture of pellets independently polymerized and polyethylene terephthalate pellets is supplied to an extruder and copolymerized by transesterification at the time of melting. Moreover, as long as film forming property is not affected as a film, trimellitic acid, pyromellitic acid and an ester derivative thereof may be copolymerized in a small amount.

  Moreover, as long as the object of the present invention is not impaired, the polyester resin may contain 5% by mass or less of a resin compatible with the polyester resin other than the polyester resin with respect to the total mass of the resin component.

  The thermoplastic resin (B) incompatible with the polyester resin includes olefin resins such as polyethylene, polypropylene, polybutene, polymethylpentene, and cyclic olefin, styrene resins, polyacrylate resins, polycarbonate resins, polyacrylonitrile resins, Polyphenylene sulfide resin, fluorine resin, etc. are selected. Of these, olefin-based resins or styrene-based resins are preferable. Examples of olefin-based resins include polyethylene, polypropylene, and poly-4-methylpentene-1 (hereinafter, may be abbreviated as “polymethylpentene” or “PMP”). , Ethylene-propylene copolymer, ethylene-butene-1 copolymer, and cyclic olefin, and polystyrene, polymethylstyrene, polydimethylstyrene, and the like are preferable as the styrene resin. These may be a homopolymer or a copolymer, and two or more thermoplastic resins (B) may be used in combination. It is preferable that 1-50 mass% of thermoplastic resins (B) are contained with respect to the total mass of the reflector of the present invention. When the thermoplastic resin (B) is less than 1% by mass, it is difficult to make the specific gravity 1.1 or less, and when it is more than 50% by mass, the mechanical strength, heat resistance and production cost of the polyester resin may be impaired. is there.

As a method for obtaining the mass ratio of the polyester resin and the thermoplastic resin (B), a method of combining a plurality of analyzes according to the type of each resin is conceivable. Only the polyester resin is removed with a solvent, the remaining thermoplastic resin (B) is separated by a centrifuge, and the mass ratio is determined from the mass of the resulting residue, IR (infrared spectroscopy), ¹ H- After identifying each resin by NMR or ¹³ C-NMR, both the polyester resin and the thermoplastic resin (B) are dissolved in a soluble solvent, impurities and inorganic substances are removed by centrifugation, and the concentration is determined by absorbance. Thus, a method for obtaining a mass ratio can be used. As a solvent in which the polyester resin is soluble, trifluoroacetic acid, 1,1,1,3,3,3-hexafluoro-2-propanol, o-chlorophenol, or the like is used.

  In the reflector of the present invention, the ratio d / D between the minimum thickness d and the maximum thickness D of the reflector having protrusions is preferably 0.5 or more and 0.8 or less. If the thickness ratio d / D is smaller than 0.5, the strength of the thin portion is inferior, so the compression strength may not be high. Further, if the thickness ratio d / D is larger than 0.8, the shape of the protrusion may not be sufficiently formed as designed. In order to make the ratio of the thicknesses within such a range, it is preferable to form a white film produced by the production method described later by the above method.

  The reflector of the present invention is preferably a reflector containing bubbles that enclose nuclei. By containing bubbles, the reflection performance as a reflector can be improved, and by including the core, the bubbles are easily maintained without being collapsed during molding. Bubbles encapsulating the core are obtained by adding the thermoplastic resin (B) incompatible with the thermoplastic resin (A) and stretching the resin uniaxially or biaxially. ) Is generated by generating fine bubbles as a nucleus. In the case of bubbles without nuclei, the reflection performance can be improved, but the bubbles may be collapsed during molding, which is not preferable.

  The reflector of the present invention preferably has a plurality of protrusions, and the difference Δh between the maximum value and the minimum value of the height is preferably 0.5 mm or less. More preferably, it is 0.3 mm or less, More preferably, it is 0.1 mm or less. Δh is obtained by (maximum value of height) − (minimum value of height). In order to withstand the load of the diffusion plate, it is preferable to support the diffusion plate with a plurality of protrusions. If the difference Δh between the maximum value and the minimum value of the plurality of protrusions is greater than 0.5 mm, the load concentrates on the high protrusions. , The protrusions may be crushed. The method of setting the difference Δh between the maximum value and the minimum value of the plurality of protrusions in such a range is not particularly limited, but can be achieved, for example, by adjusting a mold used at the time of molding.

  In the reflector of the present invention, the main component is preferably polyester. If the polyester resin is at least 50% by mass or more of the resin constituting the reflector, it can be said to be the main component.

  The reflecting plate of the present invention may be a reflecting plate composed of a single layer or a reflecting plate composed of a plurality of layers, but is preferably at least three layers. For example, a configuration in which the core layer (Y) containing bubbles inside and the surface layer (X) are laminated in three layers in the order of X / Y / X is preferable. High strength may be obtained by laminating the surface layer (X) and the core layer (Y) in the order of X / Y / X. The reflector of the present invention may be composed of four or more layers, but a three-layer structure is preferable in view of ease and strength in film formation. Further, it is preferable that the surface layer (X) and the core layer (Y) are stretched in a biaxial direction after being simultaneously laminated in the film production line by a coextrusion method. Furthermore, you may perform re-longitudinal stretching and / or re-lateral stretching as needed.

  Next, although an example is demonstrated about the manufacturing method of the reflecting plate of this invention, it is not specifically limited. In a composite film forming apparatus having two single-screw or twin-screw extruders, a main extruder and a sub-extruder, the main extruder is a resin that is a raw material for the core layer (Y), and the sub-extruder is a raw material for the surface layer (X). Add the resin to become. Each raw material is preferably dried so that the moisture content is 50 ppm or less. In this way, the raw materials are supplied to each extruder and, for example, a three-layer laminated film of X / Y / X can be formed by using two extruders and a feed block or a multi-manifold installed on the top of the T die. The extruded unstretched sheet is closely cooled and solidified on a cooled drum to obtain an unstretched laminated film. At this time, in order to obtain a uniform film, it is desirable to apply static electricity and make it adhere on the drum.

  This unstretched film is heated to a temperature equal to or higher than the glass transition temperature (Tg) of the polymer by roll heating or infrared heating if necessary, and stretched in the longitudinal direction (hereinafter referred to as the longitudinal direction) to obtain a longitudinally stretched film. This stretching is performed by utilizing the difference in peripheral speed between two or more rolls. The ratio of longitudinal stretching is preferably 2 to 6 times, more preferably 3 to 4 times, although it depends on the required characteristics of the application. If it is less than 2 times, the reflectance may be low, and if it exceeds 6 times, breakage may easily occur during film formation. The film after longitudinal stretching is then subjected to stretching, heat setting, and thermal relaxation in the direction perpendicular to the longitudinal direction (hereinafter referred to as the transverse direction) to form a biaxially oriented film. While running. At this time, preheating and stretching temperature for transverse stretching are preferably performed at a glass transition temperature (Tg) or higher (Tg + 20 ° C.) of the polymer. The transverse stretching ratio is preferably 2.5 to 6 times, more preferably 3 to 4 times, although it depends on the required characteristics of the application. If it is less than 2.5 times, the reflectance may be low. If it exceeds 6 times, breakage may easily occur during film formation. In order to complete the crystal orientation of the obtained biaxially stretched laminated film and to give flatness and dimensional stability, heat treatment is continued in the tenter at a temperature of 180 to 230 ° C. for 1 to 60 seconds, and uniform. After cooling slowly, it is cooled to room temperature and wound on a roll. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction.

  Further, here, the case of stretching by the sequential biaxial stretching method has been described in detail, but the reflector of the present invention may be stretched by any of the sequential biaxial stretching method and the simultaneous biaxial stretching method. If necessary, after the biaxial stretching, re-longitudinal stretching and / or re-lateral stretching may be performed.

  In order to impart planar stability and dimensional stability to the biaxially stretched laminated film thus obtained, heat treatment (heat setting) is subsequently performed in the tenter, and after uniform cooling, cooling to near room temperature and winding up Thereby, the white film for reflectors of this invention can be obtained.

  In addition, various coating liquids may be applied using a well-known technique in order to impart slipperiness, antistatic properties, ultraviolet light absorption performance, etc. to at least one surface of the white film within a range where the effects of the present invention are not impaired. You may apply | coat or provide a hard-coat layer etc. in order to improve impact resistance. The coating may be performed at the time of film production (in-line coating), or may be performed on a white film after film production (off-line coating).

  The reflector of the present invention can be obtained by molding a white film by the molding method described below, for example. The forming method is not particularly limited, but a method of forming only a film, such as vacuum forming, pressure forming, vacuum pressure forming, press forming, plug assist vacuum pressure forming, insert forming, TOM (Three Dimension Over Method) forming, tertiary It can be formed by a generally known forming method such as a forming method with a base material such as original laminate forming. For example, when vacuum / pressure forming is performed, the film is heated with a far-infrared heater at 400 ° C. so that the film surface temperature becomes Tg + 50 ° C. or higher, and vacuum / pressure forming is performed along a mold heated to 50 ° C. ( By performing the pressure of 1 MPa, the reflector of the present invention is obtained.

  The reflector of this invention can be used suitably as a reflector for LED lighting units. In the case of the LED lighting unit using the reflecting plate of the present invention, the distance between the LED of the light source and the diffusion plate can be maintained, and the brightness unevenness of the LED can be suppressed, which is preferable. It is particularly preferable as a reflector for a flat LED lighting unit.

  The reflector of the present invention can be suitably used as a reflector for a direct type LED backlight unit. In the case of the direct type LED backlight unit using the reflector of the present invention, the distance between the LED of the light source and the diffusion plate can be maintained, and the brightness unevenness of the LED can be suppressed, which is preferable. Particularly, it is preferable as a reflector for a direct type LED backlight unit used for a liquid crystal display, a liquid crystal television, a liquid crystal monitor, and the like.

  Hereinafter, the present invention will be described in detail by way of examples. Each characteristic value was measured by the following method.

(1) Height of projection, bottom width, S _(x) , S _(y) , S _{(2 / 3h)} / S _{(1 / 3h),} Δh
About the shape | molded processus | protrusion, the shape was measured with the one shot 3D shape measuring machine VR-3200 (made by Keyence Corporation). The height of the protrusion is measured as follows. First, a circle (circumscribed circle) profile (hereinafter referred to as a circle profile 1) that completely surrounds the protrusion around the protrusion tip is drawn. Next, the radius is set to (radius of circle profile 1 + 3 mm), and a circle profile (hereinafter referred to as circle profile 2) is acquired. The vertical distance from the point indicating the maximum height on the obtained circular profile 2 to the tip of the protrusion was defined as the height of the protrusion. However, the part which overlaps within 3 mm of other protrusions is excluded from the profile. The bottom width was determined by observing the protrusion from directly above, and taking the longest width as the bottom width. Moreover, the cross-sectional area at the time of cutting a processus | protrusion by x and y of processus | protrusion height was each calculated | required by VR-3000Series application analysis application, and S _(x) / S _(y) was calculated | required. Similarly, the cross-sectional areas when the protrusions were cut at 1/3 and 2/3 of the protrusion height were determined, and S _{(2 / 3h)} / S _{(1 / 3h)} was determined. In the reflector having a plurality of different protrusions, the heights of all the protrusions were measured, and the difference Δh between the maximum value and the minimum value of the protrusion height was obtained. Further, in the reflector having a plurality of different protrusions, the bottom width and S _{(2 / 3h)} / S _{(1 / 3h)} in the protrusion having the maximum protrusion height are employed.

(2) Specific gravity Five square samples each having a side of 5 cm are cut out so that one or more protrusions are included from the reflector, and each is based on JIS K7112-1980. Electronic hydrometer SD-120L (Mirage Trading Co. ). The arithmetic average of the obtained measured values of a total of five points was calculated | required, and it was set as specific gravity of the reflecting plate which has the said processus | protrusion. When the bottom width was larger than 5 cm, the sample was cut out so as to include the tip of the protrusion. It should be noted that even if the reflecting plate has a hole and a part of the shape is missing, measurement can be performed without any problem.

(3) Maximum thickness D, minimum thickness d, d / D
The thickness of the reflecting plate was measured by attaching a carbide needle probe φ0.45 mm to a dial gauge type thickness meter (manufactured by Mitutoyo Corporation). The thickness at the tip of the protrusion is measured. Moreover, the thickness on the circular profile 2 obtained above is measured. The thickness was measured at five points on the tip of the protrusion and on the circular profile 2, and the maximum thickness was D and the minimum thickness was d.

  If the shape is small and it is difficult to measure even with a needle probe, when measuring the thickness of a film in a minute region, cut out the cross section perpendicular to the surface direction of the reflector using a microtome and deposit platinum-palladium. The target region is observed at an arbitrary magnification between 200 times and 1,000 times with a field emission scanning electron microscope “JSM-6700F” manufactured by Electron Co., Ltd., and a cross-sectional observation photograph is obtained. The thickness of the straight line connecting the front surface side and the back surface side of the reflector in the cross-sectional observation photograph with the shortest distance is defined as the thickness.

  The maximum thickness thus obtained was defined as the maximum thickness D, and the minimum thickness was defined as the minimum thickness d.

(4) Load resistance The protrusion was subjected to a compression test using a high elongation measuring device (Boldwin Co., Ltd., RTF-1210) and a compression test jig. Test conditions are in accordance with JIS K7181: 2011 until the protrusions are buckled, and the boundary between elastic deformation and plastic deformation (Fig. 1) is read from the obtained SS curve, and the load resistance is determined from the test force (N). evaluated.

(5) Optical unevenness As shown in FIG. 2, four holes with a diameter of 12 mm were formed in the center of the portion surrounded by the four protrusions. The lens cap was removed from the LED bar of a commercial TV (manufactured by Haier, LE42A7000), and a reflector was set so that the LED would come out of the hole. The optical film group was placed on the reflector and the LED was turned on to observe the appearance.
A: The LED and the optical film group are separated and unevenness is suppressed. O: The LED and the optical film group are close to each other, but the unevenness is somewhat suppressed due to a gap. Δ: Contact between the protrusion and the optical film group. Although the portion is likely to be uneven, it is suppressed by the optical film group x: The LED is in contact with the optical film group.
△ or more was accepted.

[Raw materials]
(1) PET resin (a)
Polymerization was carried out from terephthalic acid and ethylene glycol by a conventional method using antimony trioxide as a catalyst to obtain polyethylene terephthalate (PET). The obtained PET has a glass transition temperature of 77 ° C., a melting point of 255 ° C., an intrinsic viscosity of 0.63 dl / g, and a terminal carboxyl group concentration of 40 eq. / T.

(2) Cyclic olefin (COC) resin (b)
A commercially available cyclic olefin resin “TOPAS 6017” (Nippon Polyplastics Co., Ltd.) was used.

(3) Titanium dioxide 50 mass% master (c)
50 parts by mass of PET resin (a) and 50 parts by mass of titanium dioxide particles (number average particle size 0.5 μm) were kneaded with a twin screw extruder to obtain a titanium dioxide 50% master (c).

(Examples 1 to 19)
The raw materials having the composition shown in Table 1 were vacuum-dried at a temperature of 180 ° C. for 6 hours, and then the raw material for the core layer (Y) was supplied to the main extruder and melt-extruded at a temperature of 280 ° C. and filtered through a 30 μm cut filter. After supplying the raw material of the surface layer (X) to the sub-extrusion machine and filtering through a 30 μm cut filter after melt extrusion at a temperature of 280 ° C., the surface layer (X) is the core layer (Y) in the T-die composite die. It was made to merge so that it might be laminated | stacked on a surface layer (X / Y / X).

  Next, the sheet was extruded into a molten sheet, and the molten sheet was closely cooled and solidified by an electrostatic application method on a drum kept at a surface temperature of 25 ° C. to obtain an unstretched film. Subsequently, the unstretched film was preheated with a roll group heated to a temperature of 80 ° C., and then stretched 3.3 times in the longitudinal direction (longitudinal direction) while being irradiated from both sides with an infrared heater. It cooled with the roll group of temperature, and obtained the uniaxially stretched film. Thereafter, both ends of the uniaxially stretched film were guided to a 110 ° C. preheating zone in the tenter while being gripped by clips, and subsequently stretched 3.5 times in a direction perpendicular to the longitudinal direction (lateral direction) at 120 ° C. Subsequently, a heat treatment of 200 ° C. was performed in a heat treatment zone in the tenter, and after uniform cooling, the film was wound on a roll to obtain a white film.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it could be molded with the height and width of the right cone-shaped protrusions shown in Table 2, and a reflector designed so that the distance between the tips of the protrusions was 5 cm was obtained.

(Comparative Examples 1-4)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it could be molded with the height and width of the right cone-shaped protrusions shown in Table 2, and a reflector designed so that the distance between the tips of the protrusions was 5 cm was obtained.

  Since the height of the protrusion was less than 1 mm, the LED and the optical film group contacted each other.

(Comparative Example 5)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. A mold was designed so that it could be molded with the height and width of the columnar protrusions shown in Table 2, and a reflector designed so that the distance between the centers of the protrusions was 5 cm was obtained.

  Since the height of the protrusion was less than 1 mm, the LED and the optical film group contacted each other. Further, the shape of the protrusion was not a shape in which the horizontal cross-sectional area decreased according to the height, so that the load resistance was less than 3N.

(Comparative Example 6)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. A mold was designed so that it can be molded with the height and width of the oblique cone-shaped protrusions shown in Table 2 and FIG. 3, and a reflector designed so that the distance between the tips of the protrusions was 5 cm was obtained.

  Since the height of the protrusion was less than 1 mm, the LED and the optical film group contacted each other. Moreover, about the shape of protrusion, since the gravity center of the bottom face and the gravity center of the whole solid do not match in the film thickness direction, the load resistance was less than 3N.

(Example 20)
A white film was obtained in the same manner as in Example 1.

  Vacuum / pressure forming was performed in the same manner as in Example 1 using a molding machine manufactured by Asano Laboratories (FKS-0631-20). The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it could be molded with the height and width of the right conical protrusions shown in Table 2, and a reflector designed so that the distance between the protrusion tips was 10 cm was obtained.

(Example 21)
A white film was obtained in the same manner as in Example 1.

  Vacuum / pressure forming was performed in the same manner as in Example 1 using a molding machine manufactured by Asano Laboratories (FKS-0631-20). The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. A mold was designed so that it can be molded with the height and width of the oblique cone-shaped protrusions shown in Table 2 and FIG. 3, and a reflector designed so that the distance between the tips of the protrusions was 10 cm was obtained.

(Examples 22 and 23)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. A mold was designed so that it could be molded with the height and width of the columnar protrusions shown in Table 2, and a reflector designed so that the distance between the centers of the protrusions was 5 cm was obtained.

(Examples 24-31)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The mold is designed so that it can be formed with the height and width of the truncated cone-shaped protrusions shown in Table 2 and the upper bottom width of the frustum, and a reflector that is designed so that the distance between the centers of adjacent protrusions is 5 cm is obtained. It was.

(Example 32)
A white film was obtained in the same manner as in Example 1.

  Using a molding machine manufactured by Asano Laboratories (FKS-0631-20), heat the film so that the film surface temperature becomes Tg + 50 ° C. or higher with a 400 ° C. far-infrared heater. Along with this, vacuum / pressure forming (pressure: 1 MPa) was performed. The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. A mold was designed so that it could be molded with the height and width of the hemispherical protrusions shown in Table 2, and a reflector designed so that the distance between the centers of adjacent protrusions was 5 cm was obtained.

(Examples 33 and 34)
A white film was obtained in the same manner as in Example 1.

  Vacuum / pressure forming was performed in the same manner as in Example 1 using a molding machine manufactured by Asano Laboratories (FKS-0631-20). The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it can be molded with the height and width of the regular triangular pyramidal projections shown in Table 2, and a reflector designed so that the distance between the tips of the projections was 10 cm was obtained.

(Examples 35 and 36)
A white film was obtained in the same manner as in Example 1.

  Vacuum / pressure forming was performed in the same manner as in Example 1 using a molding machine manufactured by Asano Laboratories (FKS-0631-20). The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it could be molded with the height and width of the regular quadrangular pyramidal protrusions shown in Table 2, and a reflector designed so that the distance between the tips of the protrusions was 10 cm was obtained.

(Examples 37 and 38)
A white film was obtained in the same manner as in Example 1.

  Vacuum / pressure forming was performed in the same manner as in Example 1 using a molding machine manufactured by Asano Laboratories (FKS-0631-20). The mold used was a shape as shown in FIG. 2 on a 30 cm square base, with nine protrusions arranged at equal intervals so as to form 3 rows × 3 columns. The metal mold was designed so that it could be molded with the height and width of the regular quadrangular pyramid shaped projections shown in Table 2, and a reflector designed so that the distance between the centers of the projections was 10 cm was obtained.

(Example 39)
The raw materials having the composition shown in Table 1 were vacuum-dried at a temperature of 180 ° C. for 6 hours, the raw material for the core layer (Y) was supplied to the main extruder, melt-extruded at a temperature of 280 ° C., and filtered through a 30 μm cut filter. Introduced into die die.

  Subsequently, it was extruded into a sheet shape to obtain a molten sheet. Thereafter, a white film was obtained in the same manner as in Example 1.

  Vacuum forming was performed in the same manner as in Example 1 to obtain a reflector.

(Reference Example 1)
A white film was obtained in the same manner as in Example 1. This white film was used as Reference Example 1. Since there was no protrusion, the LED and the optical film group contacted each other.

  ADVANTAGE OF THE INVENTION According to this invention, the reflecting plate which integrated the pin excellent in the intensity | strength which supports a reflecting plate and a diffusion plate can be provided.

It is a figure showing a compression test SS curve. It is a figure showing the sample drawing for optical evaluation. It is a figure showing drawing of an oblique cone-shaped protrusion.

11: Protrusion 12: Plane portion 13: Hole

Claims (12)

A reflector having protrusions with a height of 1 mm or more. The reflector according to claim 1, wherein the load resistance of the protrusion is 3N or more. The reflector according to claim 1 or 2, wherein the maximum thickness D is 400 µm or less. The reflecting plate according to claim 1, wherein a horizontal cross-sectional area of the protrusion decreases with height. The reflecting plate according to claim 1, wherein the reflecting plate has a specific gravity of 0.5 or more and 1.1 or less. The reflective plate according to claim 1, wherein a ratio d / D of the minimum thickness d and the maximum thickness D of the reflective plate having protrusions is 0.5 or more and 0.8 or less. The reflecting plate according to any one of claims 1 to 6, comprising a bubble enclosing a nucleus. The reflection plate according to claim 1, comprising a plurality of the protrusions, and a difference Δh between a maximum value and a minimum value of the height is 0.5 mm or less. The reflecting plate according to any one of claims 1 to 8, wherein the main component is polyester. The reflector according to claim 1, comprising at least three layers. The reflector in any one of Claims 1-10 used for a LED lighting unit. The reflector in any one of Claims 1-10 used for a direct type | mold LED backlight unit.

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